A reprographic system includes a scanner for scanning paper documents and pictures and storing them into electronic files, image processing software and/or hardware for storing, transmitting, and manipulating the files, and a printer for printing copies of the processed images. Traditional reprographic systems are ‘closed’ systems having a dedicated, integrated scanner and printer like a photocopier. The dedicated scanner and printer are initially calibrated to operate together by the manufacturer and, after the copier is installed, periodically by a specialized service technician. Technicians manually calibrate the systems with tools and reference materials unavailable to average users and with specialized training.
Modern reprographic systems are moving toward a modular structure, often supporting multiple scanners and multiple printers in a defined architecture. Such systems can also include other output destinations for images, such as facsimile, e-mail, etc. and individual components have unique image characteristics. Manual calibration of these individual components quickly becomes cumbersome, especially for calibration of and selection of enhancement tools for color components.
Color components add to the complexity of calibration since color scanning components typically generate data in a red, green, and blue (RGB) color space and printers typically print in a cyan, magenta, and yellow (CMY) color space or a cyan, magenta, yellow, and black (CMYK). Thus, in color systems, calibration must not only account for differences in tone levels of black, but also variances in three other color levels and interrelationships between the color levels and distortions related to different processing techniques of the various components. More specifically, when a color scanner scans a color image, a mix of, e.g., red, green, and blue bits represent each color of the image including black. Distortions involved with the scanning process can cause one or more, or even all of the hues in the color image to be misrepresented by the scanner with regards to color values of pixels and pixel locations. With regards to sharp black images like black text, misalignments of the scanner optics can cause misalignments of pixels, changing black pixels of the text into pixels with one or more color casts.
Distortions involved with color printing processes can cause the red, green, and blue pixels to be misrepresented in CMYK color space on paper, further compounding the errors. Such distortions, which are inherent to color document reproduction on a modular, reprographic system, require multiple combinations of complex image correction or enhancement processes. The number and settings for each of the multiple combinations depend upon the distortions associated with a selected scanner and printer and the original document to be reproduced, as well as how these distortions interact. Having an average user select each the image enhancement algorithms and their settings to produce a suitable copy each page of each document is an impracticable solution for most applications, but failing to adequately correct for distortions, even if an acceptable copy of a high quality original can be made, would significantly degrade image quality as copies are reproduced.